FDA Lets MS Drug Tysabri Return

More Cases Possible continued...

Speaking about PML, Katz says, “We don’t know how to predict who’s going to get it, we don’t know how to prevent it, and we don’t know how to treat it if it occurs.”

Galson notes that until Tysabri’s new risk-minimization program has been in effect for some time and physicians have seen patients go through rounds of therapy, “there may be additional things that we will learn.”

“The size of the clinical trials that have taken place and the duration is not adequate for us to know for certain that there isn’t something else that’s going to happen or further information that will be gained about this condition,” Galson says.

“We made the assessment that the benefits of this drug outweigh the risk for this particular condition,” Galson says. “Multiple sclerosis … is a debilitating condition and we are certain that patients are willing to take this risk because of the potential benefits of the drug. So that’s why we’re doing it.”

About Tysabri

Tysabri is a monoclonal antibody given usually once a month by health care professionals. It’s used to treat patients with relapsing forms of MS in order to reduce the frequency of flare-ups.

The new rules mean that before taking Tysabri, patients must enroll in a risk-minimization program designed by Biogen-Idec. Patients also need to get a brain scan using magnetic resonance imaging (MRI) before taking Tysabri.

Doctors who prescribe Tysabri, pharmacies that dispense the drug, and infusion sites that administer the drug must also enroll in the risk-minimization program.

Tysabri shouldn’t be used in combination with other immune-system modifying drugs. It’s intended for patients who have not responded adequately to -- or cannot tolerate -- other treatments for MS, states the FDA. However, other uses of Tysabri aren’t forbidden on the label.

Risk-Minimization Plan

In February 2005, after Biogen-Idec took Tysabri off the market, the FDA put Tysabri’s clinical trials on hold.

A year later, the FDA let a Tysabri clinical trial resume after a re-examination of patients in Tysabri’s previous clinical trials confirmed no additional cases of PML.